This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The kinetochore is a multi-protein complex that assembles on the centromere and attaches chromosomes to spindle microtubules during cell division. Kinetochore attachments are tightly monitored to ensure faithful chromosome segregation. A recent genome-wide yeast two-hybrid screen focusing on the mitotic spindle identified interactions between the essential kinetochore protein Mif2 (S. cerevisiae homolog of human CENP-C) and two Casein Kinase 2 (CK2) subunits, Cka2 and Ckb2. CK2, a ubiquitous and highly conserved kinase in eukaryotes, is composed of two catalytic subunits (Cka1 and Cka2) and two regulatory subunits (Ckb1 and Ckb2). Although CK2 has been linked to a variety of cellular processes, how CK2 regulates these diverse events is largely unclear. In this study, we investigated the roles of CK2 in mitotic spindle function.